I'd take issue a different way.
It seems far more likely that objects like 'Oumuamua are relatively rare, and that means it likely came from someplace close by (if it came from farther away, the odds are even lower we'd ever see one).
I'd rather look at the density of Oumuamua-like objects in space. First, it seems like these objects rarer than some things but dense enough for us to have seen them.
Their "terminal density" comes when their rate of production managers to equal their rate of consumption. Who knows how they're produced but I'd assume they are consumed when they are gravitationally captured by a solar system - actually flying into a sun is much less likely I'd assume. Such gravitational capture is more likely if these objects are moving at a similar speed to the solar system they encounter.
The one thing we know about Oumuamua is it seemed to speed up as it left the solar system. This factor might imply that the chances of capture wind-up very low. Now, the rate of production could be low and thus life-span could be high. A high lifespan implies this came from far away. I could be wrong on the consumption chances. But still, I think arguments about how far these travel would do better with such life span analysis than with the quote argument, whose implications are foggy imo.
As to whether the thing is a product of alien intelligence? If the very low density analysis is correct, if such a thing could behave as Oumuamua did, then that too might be a good spacecraft design. Which is to say, the amount of information we have is low that making absolute answer seems pretty hard here.